Energy in the sun gets out by
A. circulating gases.
B. emission of photons.
C. interacting with electrons.
D. all of the above.

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The sun is mostly hydrogen with about 25% helium and small amounts of heavier elements.
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At different temperatures the gases behave differently forming layers.
core radiative zone convective zone photosphere

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Inside the sun the gas is acted on by forces.
–
Gravity inward
–
Pressure outward
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The balance is called hydrostatic equilibrium .
–
Density and temperature increase inside
–
Computer models

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Surface Temperature:
• Core Temperature:
5,800 K
15,000,000 K
• The sun produces 10 27 cal/min at its surface (4

10 26 W).
• This is equivalent to 100 billion 1 megaton hydrogen bombs every second!!
•
This energy produced in the Sun flows out as light and other electromagnetic energy.

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In the core all gas is ionized and forms a plasma .
–
Temperatures up to 15,000,000 K
– Density up to 100 g/cm 3
•
This is where fusion occurs.
photons neutrinos

photons
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Outside of the core is the radiation layer .
–
Temperature drops from
5,000,000 to 100,000 K
– Still plasma
–
Too cool for fusion
•
Photons work their way out through the layer.
– Absorption and reradiation
–
Typically 170,000 years

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The highest 20% of the sun is the convection layer .
• The temperature drops from 100,000 to 6,000 K.
• The hydrogen and helium are a gas again with no fusion.
• Energy is transferred through convection, the movement of gas to and from the surface (“hot” air rises).
photosphere convection layer radiative layer

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Sound waves move through the Sun like earthquakes.
–
Velocity ripples on surface
– Probes interior
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The Global Oscillation Network Group tracks solar sound waves.